1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to a vibrating element, a fabrication method thereof, and an ultrasonic motor having the same, and more particularly, to a vibrating element, which can be easily fabricated while having a simplified structure and an improved reliability, a fabrication method thereof, and an ultrasonic motor having the same.
2. Description of the Related Art
Generally, an ultrasonic motor, for example, a traveling wave type hollowed ultrasonic motor includes a vibrating element to generate a vibration, and a contacting element to rotate while coming in friction contact with the vibrating element according to the vibration of the vibrating element. To generate the vibration, the vibrating element is provided with a piezoelectric body, which generates deformations or displacements due to a piezoelectric effect when it is applied with a voltage having a high frequency of, for example, more than audio frequency. The contacting element rotates while coming in friction contact with the vibrating element according to the vibration of the vibrating element caused by the piezoelectric body.
In such an ultrasonic motor, a performance is dependent upon vibrating displacements of the vibrating element. Thus, to enlarge the vibrating displacements of the vibrating element, it is advantageous that the piezoelectric body generates the deformations as large as possible.
As an example of the piezoelectric body, there is generally known a single-layered piezoelectric body, which is made of one piezoelectric layer. The single-layered piezoelectric body is advantageous in that it can be easily fabricated and it is easy to form electrodes thereon for applying a voltage to the piezoelectric layer. However, because the piezoelectric layer is relatively thick, a relatively high voltage should be applied to the piezoelectric layer in order to produce a large electric field.
To address the problem as described above, a multi-layered piezoelectric body in which a plurality of piezoelectric layers are layered and electrodes are disposed between the piezoelectric layers has been proposed and used. The multi-layered piezoelectric body is configured so that each of the piezoelectric layers has a very thin thickness, for example, a thickness of several tens of microns. Thus, even though each of the piezoelectric layers is applied with a low voltage, an electric field produced on the multi-layered piezoelectric body increases in strength. However, because each of the electrodes disposed between the piezoelectric layers has a very thin thickness of, for example, several ten microns, connecting the electrodes with lead wires is very difficult and causes the motor to have a complicated construction. Also, even though the electrodes are connected with the lead wires, it is difficult to guarantee reliability in electrode connection.
To address the problem as described above, a method of forming holes in the respective piezoelectric layers and connecting the electrodes through the formed holes has been proposed. However, forming the holes in the respective piezoelectric layers requires a complicated fabrication process and increases the fabrication cost.
Accordingly, there is a need to develop an ultrasonic motor having an electrode connecting part capable of being easily fabricated while having a simplified structure and an improved reliability.